eu.stratosphere.arraymodel.example

Class WordCountArrayTuples.CountWords

java.lang.Object

eu.stratosphere.api.common.functions.AbstractFunction

eu.stratosphere.arraymodel.functions.AbstractArrayModelFunction

eu.stratosphere.arraymodel.functions.ReduceFunction

eu.stratosphere.arraymodel.example.WordCountArrayTuples.CountWords

All Implemented Interfaces:

Function, GenericReducer<Value[],Value[]>

Enclosing class:

WordCountArrayTuples

public static class WordCountArrayTuples.CountWords
extends ReduceFunction

Sums up the counts for a certain given key. The counts are assumed to be at position 1 in the record. The other fields are not modified.

Constructor Summary

Constructors

Constructor and Description
WordCountArrayTuples.CountWords()

Method Summary

Methods

Modifier and Type	Method and Description
void	reduce(Iterator<Value[]> records, Collector<Value[]> out) The central function to be implemented for a reducer.

Methods inherited from class eu.stratosphere.arraymodel.functions.ReduceFunction

combine, getUDFMethod

Methods inherited from class eu.stratosphere.arraymodel.functions.AbstractArrayModelFunction

getDataTypes

Methods inherited from class eu.stratosphere.api.common.functions.AbstractFunction

close, getIterationRuntimeContext, getRuntimeContext, open, setRuntimeContext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface eu.stratosphere.api.common.functions.Function

close, getRuntimeContext, open, setRuntimeContext

Constructor Detail

WordCountArrayTuples.CountWords

public WordCountArrayTuples.CountWords()

Method Detail

reduce

public void reduce(Iterator<Value[]> records,
          Collector<Value[]> out)
            throws Exception

Description copied from class: ReduceFunction

The central function to be implemented for a reducer. The function receives per call one key and all the values that belong to that key. Each key is guaranteed to be processed by exactly one function call across all involved instances across all computing nodes.

Specified by:

reduce in interface GenericReducer<Value[],Value[]>

Specified by:

reduce in class ReduceFunction

Parameters:

records - All records that belong to the given input key.

out - The collector to hand results to.

Throws:

Exception - Implementations may forward exceptions, which are caught by the runtime. When the runtime catches an exception, it aborts the reduce task and lets the fail-over logic decide whether to retry the reduce execution.